Cathode ray scanning device



24, 1942. w. HEIMANN 2:27 71101 CATHODE RAY SCANNING DEVICE Filed March 3l. 1939 nll-flnmmr y afperimentally.

Patented Mar. `24,1942

v UNIT-so 2,211,101 cA'rnoDE aar scANNINc nsvrcn Waltcr Heimann, Berlin, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application l In March 31, 1939, 'serial 10.265526 Germany March 30, 1938 4 Claims. (Cl. P18- 7.2)

In the operation of cathode ray scanning devices it has been found that disturbing impulsesare superimposed upon the useful picture impulses. `Such disturbing impulses are due to Oscillographic records have.

various causes.

shown that after each line or picture scanning an impulse occurs which is particularly strong` and acts in opposition to the useful picture impulse.' This counteracting impulse causes the edge portions of the picture to be greatly darkened. It is therefore desirable to`provide forv weakening this impulse or for obviating it.

In accordance with the invention the mosaic screen is fitted with an arrangement that shall enable the useful picture signals to be separated from disturbing One embodiment of the invention is shown in the accompanying drawing, in which Fig. 1 is a diagrammatic end view of a mosaic screen as provided` by the invention, Fig. 2 is a partially sectioned side view thereof.

The mosaic screen comprises a metal plateS, which is the so'called signal plate, a layer P composed in well knownmanner of Ametal particles and an insulating material in which these are embedded, andan insulating layer Q between S and P. Layer P is generally designated as photoelectric or mosaic layer.

'Ihe signal plate S is surrounded with a frame R constituted -.by an electrically conductive layer which. is thus arranged on the same side ofthe layer Q as the plate S. Plate S is insulated from the frame R by a strip i. The outer edge of the frame R coincides with that of layer P, that is,

' with' the edgeof the surface available for the scanning operation. vIn order thatv the useful picture surface be not much decreased in this way the frame R should not be broaderthan is `necessary. The width-thereof maybe ascertained exe In order toseparate the useful picture signals and the disturbing signals from each other frame R is directly connected to earth While plate S is grounded through-a. resistance r. The picture voltages arising atr are conveyed to an amplier not represented in the drawing.

Instead of the frame R here shown by way'of example,.metal strips may be arranged on two sides of the plate S. Also, separate metal strips may be provided on all the sides thereof. Such two or more strips are then earthed conjointly. In the case of such subdividedframe a modication of the invention would be to ground the frame in part only, thus providing for parts thereof notgrounded. i

y What is claimed is:

1. A cathode ray scanning device comprising anV insulating member, a mosaic screen comprising a layer of photoelectric material mounted on one surface of said member, a conductive signal plate mounted on the lopposite surface -of said member, a conductive, frame-shaped, layer encircling said signal plate and insulated therefrom.

mounted on said opposite surface of said member, saidsignal plate and at least a portion of said frame-shapedv layer being directly behind, in capacitative relation with and in close proximity to said screen, and means for grounding said layer.

2. A device according to claim 1, wherein the frame-shaped layer ls a closed structure.

4 3.'A device according to claim l, wherein the frame-shaped layer is 'a discontinuous structure whose parts areearthed conjointly.

4. A device according to claim 1, wherein the frame-shaped layer is a discontinuous structure a part .only of which is grounded.

' wAL'rsanEmANN. 

